The present invention relates to a method of forming a filamentary reinforced article.
A method of making a filamentary reinforced article is disclosed in U.S. Pat. No. 4,305,449. The article disclosed in this patent has a tubular configuration and has reinforcing filaments of boron, carbon, silicon carbide, or the like disposed in an aluminium or titantium matrix material. The reinforcing filaments extend axially along the tubular article. The tubular article is formed by expanding monolayers radially outwardly against a tubular mold.
A similar method of forming a tubular article is disclosed in U.S. Pat. No. 3,788,926. To make the article disclosed in this patent, four layers of boron/aluminum tape are wrapped to form a tube. Silicon carbide coated boron fibers are disposed in the layers and extend axially of the tube. The layered tube of boron/aluminum tape is enclosed in a tubular housing having a relatively heavy outer wall and a relatively thin inner wall. The housing is subjected to a hot isostatic pressing operation and the inner wall of the tube expanded outwardly to form a consolidated filamentary reinforced article.
The methods disclosed in these patents are not satisfactory to produce circular or noncircular rings and disks having thick filament reinforced walls where the axes of the filaments are oriented at a substantial angle to the central axis of the ring or disk. This is because, during a hot isostatic pressing operation, the reinforcing filaments tend to crack and/or buckle. The cracking and/or buckling occurs because the reinforcing filaments do not increase or decrease in length under the influence of tension or compression forces.
If a composite layered preform having reinforcing filaments oriented at a substantial angle to the axis of the preform is made with an open center, during a hot isostatic pressing operation, the fluid pressure against the inner layers will cause these layers to tend to increase in size and will subject the filaments to tension forces which may crack the filaments. During the hot isostatic pressing operation, the fluid pressure against the outer layers will cause these layers to tend to decrease in size and will subject the filaments to compression forces which may cause the filaments to buckle. The cracking and/or buckling of the filaments in a filamentary reinforced article is very detrimental to the operating characteristics of the article.